1. Field of the Invention
The present invention relates to a plasma lighting system, and more particularly to a plasma lighting system, a Color Rendering Index (CRI) of which may be adjusted.
2. Discussion of the Related Art
In general, a lighting system using microwaves (several hundred MHz to several GHz) is designed to generate visible light by applying microwaves to an electrodeless plasma bulb.
The microwave lighting system is an electrodeless discharge lamp in which a quartz bulb having no electrode is filled with inert gas.
Recently, the microwave lighting system is configured to emit a continuous spectrum in a visible light range via high voltage electrical discharge of sulfur. The microwave lighting system is also referred to as a plasma lighting system.
Meanwhile, Color Rendering Index (CRI) is one metric of a light source, and represents a light source's ability to show object colors realistically or naturally. That is, CRI is a numerical value representing similarity between the original color of an object and the color of the object under specific lighting.
The plasma lighting system has optical properties of continuous spectra due to use of sulfur as a dose. However, when sulfur is used as a dose, a CRI of the plasma lighting system is about 80, which is lower than that of a general High Intensity Discharge (HID) lighting system.